Origins

Niklot was a lord of the Wendish tribe of Obotrites. When the Holy Roman Empire expanded eastwards, notably to the coast of Baltic in 13th century, a portion of Obotrite lords allied with German leaders, and strengthened their own position in consequence. The mightiest of them were those who became first Lords of Mecklenburg (name derives from their main castle, Mikla Burg, big fortress). The main branch of the house was elevated in 1347 to ducal rank. They gradually became outwardly more German, preserving their ruling position.

Claims to Swedish throne

The Dukes of Mecklenburg pursued from 14th century a claim to inheritance in Sweden: The Duke of Mecklenburg was a descendant and the heir of two women whom legends tied to Scandinavian royal houses.

Duke Henry II of Mecklenburg's paternal great-grandmother, a Scandinavian noblewoman named Christina, who was the wife of Henry Borwin II of Mecklenburg (d 1226), was a daughter of King Sverker II of Sweden by his first wife. Christina was the mother of John I of Mecklenburg, whose son was Henry I of Mecklenburg.

Duke Henry II of Mecklenburg's maternal grandmother, a lady named Marianna, who was the first wife of Duke Barnim I of Pomerania (d 1278), lord of Wolgast, was a sister of King Eric XI of Sweden. Marianna had given birth to an only surviving child, daughter named Anastasia of Pomerania, who then became the wife of Henry I of Mecklenburg (d 1302) and mother of Henry II.

The Sverker dynasty had long been extinct, having lost the throne ultimately to Eric XI. The male dynasty of Eric X was also now extinct, and issue of his other daughters had been sidestepped by Birger Jarl, the husband of his daughter (the only who yet in 1250 lived), Ingeborg Eriksdotter of Sweden. Birger took care to secure the kingship to his own sons.

Claim became reality for a brief reign: Henry II's son Albert II, Duke of Mecklenburg (1318–79) married a kinswoman, a Scandinavian heiress Euphemia of Sweden and Norway (born 1317 and died 1370). The couple's second son duke Albert III deposed his uncle from the Swedish throne, and ascended as King.

The Regent-Queen Margaret chose Eric of Pomerania as her heir. Eric descended from the elder brother of Albert III. Monarchs of the Kalmar union were all cognatic descendants of the House of Mecklenburg.

The agnatic House of Mecklenburg, descended from Euphemia's youngest son Magnus I, Duke of Mecklenburg, continued to keep their claim to the throne, and occasionally stirred the situation in Scandinavia.

Claims to Norway

This country, the Hereditary Kingdom of Norway, has been the only medieval Scandinavian realm whose kingship was hereditary, not elective. Already when Olav IV of Norway was little and his mother Margaret was regent, the Dukes of Mecklenburg advanced their claims.

When Olav IV died in 1387, Norway was without a monarch, under the government of the regentess Margaret. She soon chose an heir, Eric of Pomerania, whose mother Maria of Mecklenburg had been Eufemia's eldest granddaughter. Maria's uncle, Margaret's old opponent was left without.

When Eric's nephew king Christopher died (before the death of the deposed Eric III of Norway), after some hiatus another magnate, Christian VIII of Oldenburg, of a female descent from Eufemia and the Mecklenburg (Eufemia's daughter's great-grandson), was in 1450 chosen as king of Norway, this time surpassing his cousin and male-line rival, Duke Henry the Fat of Mecklenburg.

The Dukes of Mecklenburg continued to regard themselves as rightful heirs of Norway, however they were unable to gain the kingdom from the Oldenburgs.

Modern states in Mecklenburg

Around 1711, a treaty was made between Dukes of Mecklenburg and the Elector of Brandenburg through which the elector was recognized as the next heir of Mecklenburg after the male lines of the genealogical house of Mecklenburg. Whereby the electors, later kings of Prussia, regarded themselves as having become members of the House of Mecklenburg and started to use its titles, e.g. Duke of Mecklenburg, among their own titulary.

The legality of that treaty concession has been and is under discussion, because not each of the then agnates of the House participated in the deed, and at least one of them was then underage.

In the 17th and 18th centuries, the duchy was divided several times between agnates of the ducal house. Mecklenburg-Schwerin, Werle, Mecklenburg-Güstrow and Mecklenburg-Strelitz were typical partition principalities. Until the late 18th century, most parts had returned to the senior branch (Schwerin), after which the patrimony was divided in two states until the very end of monarchy in Germany:

These were elevated to grand duchies by recognition of the Congress of Vienna. In 1918, less than a year before the elimination of monarchy, the main line of Strelitz went extinct and the then Grand Duke of Mecklenburg-Schwerin stepped in as regent, but succession unclarities (there was a junior Strelitz branch yet living in Russia) were not solved until the small monarchies both were dissolved to republics.

In addition to Duke Borwin, the current members of the House of Mecklenburg-Strelitz are his wife Duchess Alice (née Wagner; born 1959); their children Duchess Olga (born 1988), the Dukes Alexander (born 1991) and Michael (born 1994); his sisters the Duchesses Elisabeth Christine (born 1947), Marie Catherine (born 1949) and Irene (born 1952); and his uncle Duke Carl Gregor (born 1933).